The present invention relates to floating barriers for containing or controlling oil or other matter on the surface of a body of water for removal or recovery of the matter, to direct its flow, or to exclude contamination, and the invention relates particularly to floating barriers having a plurality of articulated buoyant sections.
2. Description of the Prior Art
With the growth of concern over the environmental impact of oil spills from tankers or other vessels or from leaking offshore oil and gas wells there have been numerous proposals for floating barriers or booms to contain and collect such surface contamination. These barriers fall roughly into two basic categories, "continuous" type or "segmented" type.
The continuous type barrier is usually constructed of pliable material throughout its length and therein achieves wave profile adaptibility. It normally has a flexible elongated float or series of floats that serve as a surface barrier and from which depends a sub-surface curtain of pliable material to prevent eddy currents from carrying the oil under the barrier. In the segmented type, a series of articulated buoyant sections are linked by pliable material or hinges to permit relative movement between sections in a substantially vertical plane to prevent matter from being splashed over the barrier as well as from being carried underneath it.
Examples of continuous type barriers are disclosed in U.S. Pat. No. 3,564,852, issued on Feb. 23, 1971 to M. F. Smith; U.S. Pat. No. 3,577,879, issued on May 11, 1971 to R. E. Ducrocq; U.S. Pat. No. 3,579,994, issued on May 25, 1971 to P. Preus and C. E. Rosendahl; U.S. Pat. No. 3,592,006, issued on July 13, 1971 to A. M. Crucet; U.S. Pat. No. 3,599,434, issued on Aug. 17, 1971 to L. Missud; U.S. Pat. No. 3,608,316, issued on Sept. 28, 1971 to J. E. Manuel; U.S. Pat. No. 3,613,376, issued on Oct. 19, 1971 to B. Midby, U.S. Pat. No. 3,613,377, issued on Oct. 19, 1971 to R. E. Zaugg; U.S. Pat. No. 3,630,033, issued on Dec. 28, 1971 to R. L. Tuttle; U.S. Pat. No. 3,648,463, issued on Mar. 14, 1972 to R. R. Ayers; and U.S. Pat. No. 3,667,235, issued on June 6, 1972 to P. Preus and J. J. Gallagher.
The flexibility of continuous type barriers, particularly continuous curtains, permits them to conform to gentle waves on the water surface, but the flexibility of the curtain material also allows the bottom of the barrier to balloon out and let oil pass underneath if the barrier is anchored in a current or is being used as a towed collection boom. The float's flexibility is limited, and necessarily prevents full adaptation of the barrier to wave profile in heavy waters; this results in wave action lifting the barrier above the surface of troughs between waves and permits escape of the matter to be contained. In addition, the freeboard of curtain type barriers is limited by the height of the floats, so that oil can splash over the top. Larger floats on rigid pontoons can be used, of course, but these further decrease flexibility of the barrier.
Continuous barriers, particularly the inflatable float type, can be made in relatively long lengths yet be folded for stowage. Because of the flexibility of the curtain material used in many versions of this type of barrier, flexible connections between lengths are not essential.
The sections of segmented barriers, on the other hand, can provide high freeboard and deep draft, but these barriers require some sort of flexible connecting links between the adjacent relatively rigid sections in order to conform to wave profiles. At the same time, the connections must provide an effective seal to prevent the escape of oil between the sections.
Examples of segmented barriers are disclosed in U.S. Pat. No. 3,592,005, issued on July 13, 1971 to E. C. Greenwood; U.S. Pat. No. 3,592,008, issued on July 13, 1971 to B. A. Trindle; and U.S. Pat. No. 3,645,099, issued on Feb. 29, 1972 to M. Saavedra.
In the Greenwood barrier, adjacent sections are connected by vertical axis hinges alternating with horizontal axis hinges to provide alternate hinge motion in two directions. The hinge links provide no sealing between panels, however, and must be supplemented by sheets of pliable material sealingly attached to the adjacent section ends.
The buoyant sections in the Trindle patent are connected by vertical hinges that allow limited relative angular motion between sections in the horizontal plane but essentially no relative motion in the vertical plane. The individual sections of the Trindle barrier are relatively large (20 feet long by 10 feet high), and the barrier is intended to form a relatively rigid floating wall that does not follow individual wave fluctuations. Thus, it is effective only in situations where the waves are less than the freeboard of the sections.
The sections in the Saavedra U.S. Pat. No. 3,645,099 are also connected together by a vertical axis hinge arrangement to allow relative angular motion in the horizontal plane. Relative vertical displacements are permitted by regions of accordion-pleated pliable material in the center of each panel section. Other examples of the use of the accordion principle to obtain flexibility combined with vertical stiffness in a sealed barrier include U.S. Pats. No. 3,597,924, issued on Aug. 10, 1971 to M. Risin and U.S. Pat. No. 3,611,728, issued on Oct. 12, 1971 to G. Van't Hof. Disadvantages of the accordion or fan-pleated concept are that the vertical displacement permitted is very limited and that a substantial amount of material is required for a given barrier length, with attendant increased weight and difficulty of handling.
Another prior device for connecting adjacent buoyant sections of a segmented type barrier in an articulated manner is disclosed in Swedish Pat. No. 54,003 issued in 1923. It consists of a pair of vertical plates arranged in side-by-side partially overlapping relation and pinned together near the top by a horizontal pin so that the overlapping plates can slidably rotate with respect to each other about the horizontal axis of the pin. Two tapered vertical pins, one pin welded along the outside vertical edge of each plate, slip into mating vertical slots on the ends of each of two adjacent sections so that the tapered pins of the double-plate connecter can be wedged into the corresponding slots of the adjacent sections to link them together, yet the barrier can be disassembled by lifting the double-plate connecter to withdraw the tapered pins from the slots. In the assembled condition, the tapered pins are intended to be wedged tightly into the slots, and the only motion between sections in the vertical plane is hinge motion about the axis of the above-mentioned horizontal pin. This pin must withstand all of the forces acting between adjacent sections and is a potential weak point in the connection.